HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Esslemont, G. Articles by Lawrence, I. Search for Related Content PubMed PubMed Citation Articles by Esslemont, G. Articles by Lawrence, I. Agricola Articles by Esslemont, G. Articles by Lawrence, I. Related Collections Biogeochemical Processes Nutrient Cycling

TECHNICAL REPORTS

Plant and Environment Interactions

Riparian Plant Material Inputs to the Murray River, Australia

Composition, Reactivity, and Role of Nutrients

^a Cooperative Research Centre for Freshwater Ecology, Univ. of Canberra, ACT 2601 Australia
^b Ecochemistry Lab., Institute of Applied Ecology, Univ. of Canberra, ACT 2601 Australia
^c CSIRO, Land and Water. GPO Box 1666, Canberra, ACT, 2601

^* Corresponding author (Bill.Maher{at}canberra.edu.au)

Received for publication August 15, 2006. By changing riparian plants from Eucalypts to pasture and exotic deciduous trees, modern development has altered the type of carbon assimilated by Australian rivers. To investigate influences of plant litter substrates on biochemical oxygen demand, plant materials entering the Murray River were analyzed for their composition and mineralization potential. Plant materials were distinguished compositionally by two principal components, structural carbon and macronutrients, as: (i) Eucalyptus leaves, (ii) Eucalyptus bark and Casuarina cunninghamiana seed cone, (iii) grasses, (iv) macrophytes, (v) aquatic herbs, (vi) non-eucalypt leaf (Salix, Casuarina, Acacia). Ratios of C/P (1879–14524) and C/N (65–267) were relatively high in Eucalyptus bark, while mean N/P (7–60) ratios were similar among plant materials. Terrestrial weathering increased C/P and C/N ratios, while N/P ratios remained similar, due to greater loss of N and P relative to C. Aerobic decay experiments showed that nutrient supplementation accelerated decay of all organic substrates, except for grasses that decayed efficiently without supplementation. Aquatic herbs also had substantial carbon availability, macrophytes and non-eucalypt leaves had intermediate carbon availability, while eucalypt leaf and bark had intermediate to low carbon availabilities. Because biochemical oxygen demand varies with organic substrates sampled from the Murray River, and also with soluble nutrient availability, it is plausible that that modern changes to riverine plant communities and land use have influenced the biogeochemistry of this river toward faster, and more complete, processing of allochthonous carbon.